The health field requires patient-focused strategies to reduce diagnostic error, improve health, and save lives. Diagnostic error, or diagnoses that are wrong, missed, or delayed, is a serious issue in inpatient and outpatient settings. Most proposals to improve diagnostic quality focus on physicians and healthcare systems; few engage patients - the consumers of healthcare services - in preventing, identifying, and reporting diagnostic error. This innovative project, Using Public Deliberation to Define Patient Roles in Reducing Diagnostic Error, will use deliberative approaches to engage healthcare consumers and professionals in developing informed and practical patient-focused strategies for reducing diagnostic error that are likely to have significant impacts on patient safety, healthcare delivery, and health outcomes. Specifically, the project utilizes a randomized and controlled experimental approach that involves participants from two populations (healthcare professionals and healthcare consumers). A pre-treatment survey will be administered to potential participants in both populations. Data will be used to construct four matched pair panels (two for healthcare professionals and two for healthcare consumers), a fifth unmatched panel of healthcare consumers, and a control group of healthcare professionals and consumers. All consumer panels will oversample from AHRQ priority populations. Participants in the four matched pair panels will be randomly assigned for exposure to one of two treatment conditions: (1) education about diagnostic error, or (2) education and deliberation about diagnostic error. The deliberative panels will explore the role(s) patients are willing and able to play in preventing, identifying, ad reporting diagnostic error; the strategies that should be used to enable patients to play those roles; and the systems and structures needed for patients to assume those roles. The first deliberative consumer panel will create informed recommendations about patient-focused strategies for reducing diagnostic error, which will be tested with the fifth (unmatched) deliberative consumer panel, which will also rank and prioritize the recommendations. Project evaluation will use pre-and post-test surveys administered to all panels and the control group. The evaluation design is significant and innovative because it allows for a comparison of the relative effects of no treatment, education only, and education with deliberation on both healthcare consumers and professionals. The evaluation will examine changes in perceptions, attitudes, and knowledge about diagnostic error, patient activation, health literacy, and public deliberation, among other measures. The Society to Improve Diagnosis in Medicine (SIDM) will use the recommendations to develop strategic plans, policy statements, research agendas about patient engagement in reducing diagnostic error, as well as to create a patient engagement tool kit for healthcare systems, providers, and consumers. After the project concludes, interviews will be conducted with key SIDM personnel to assess their perceptions of the quality and usefulness of the recommendations, as well as their plans for disseminating and implementing the recommendations.